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LCD TVs - LED

doubts with replacement of audio transistors

AND1007
AND1007
61
hace 5 años
hace 5 años
good friend regards I have a Chinese amplifier which I am repairing and I have a problem, I have a pre two that are a940 and the other c2073 as I don't get them I replace them with: C2073 which is: 25W to 150V at 1.5 collector current and 150 degrees by: tip31c which is from: 40w to 140vbase 100v c / e and 3rd collector current and 150 degrees but they get hot and don't leak or anything and I've already taken them out like 20 thousand times and nothing and I have the: a940 which is: 25w 150v at 1st collector current and 150 degrees by: tip42c which is: 65w 140v base and 100v c / e and 3rd collector current and 150 degrees but the equipment is not activated it is heated: /
Kastell.
Kastell.
3.058
hace 5 años

Hi, AND1007, change filters and check, comment result, these capacitors if they are bad, the TRs, are heated, by poorly filtered current.
Look at this link, you may be out of doubt.
https://www.yoreparo.com/es/tv/televisores/lcd/led/preguntas/6231218/capacimetros-y-multimetro-para-medir-el-esr-por-kastell

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sanfalla
sanfalla
1.821
hace 5 años
hace 5 años
the problem is the "HFE" (gain factor) a transistor cannot be replaced by its power its frequency must be taken into account ..... more words or less words you must mount the transistors original
AND1007
AND1007
61
hace 5 años

but because if it does not vary much for example the hfe of the a940 is: 40 and that of tip42c is: 20 for 20menos not work? I have already replaced other transistors in other equipment and well but never in an audio amplifier and I thought it would work because the tip42c is an audip that the other amplifiers use

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seekude
seekude
2.085
hace 5 años
hace 5 años
Place originals and a lot of eye ... Those transistors falsify them a lot, buy in a place of trust.
AND1007
AND1007
61
hace 5 años

friend but I want to clarify doubts because it is difficult to get those transistors the people who have them are very expensive so I ask the question
because if a d1047 transistor of power is 100w and the profit is hfe: it is 60 because the sellers of electronic spare parts replace it with a d718 transistor of 80w and the gain is 55 and it works without roll?

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seekude
seekude
2.085
hace 5 años

There are other characteristics that influence not only the gain, voltage and current. For example the bandwidth (fT). When used in audio you have to look carefully.

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seekude
seekude
2.085
hace 5 años

Looking at datasheet the a940 fT is 4Mhz and the "replacement" is 3Mhz

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manolo karvalo
hace 5 años
hace 5 años
Hello Friend. if they heat up the transistors, it may be that you have placed them inverted, because there is a data that says that the replacement of transistor a940 is tip42, c2229, and c2235, and replacement of transistor c2073, is tip 41. to google find out what he says. Cheers
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